People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Scientists from the Scripps Research Institute in California have developed a new technique that can identify patients at very high risk of a heart attack by recognizing circulating endothelial cells in the bloodstream. Photo courtesy of Shutterstock.

Suddenness and, more importantly, unexpectedness can kill in the case of heart disease. Scientists from the Scripps Research Institute in California have developed a new technique that can identify patients at very high risk of a heart attack by recognizing specific cells in the bloodstream. The researchers believe their technique, which detects the presence and number of circulating endothelial cells (CECs), can now be tested on patients who exhibit symptoms but have yet to experience a heart attack. "Our results were so significant relative to the healthy controls that the obvious next step is to assess the usefulness of the test in identifying patients during the early stages of a heart attack," said Dr. Peter Kuhn, principal investigator and program director of the Scripps Physics Oncology Center and co-author of the current study, in a press release.

Heart Disease

Coronary artery disease is a leading cause of death around the globe, and so the ability to identify people at the greatest risk of heart attack is considered the most important unmet need in cardiovascular medicine. Heart disease begins when a waxy substance called plaque builds up inside the coronary arteries, which supply oxygen-rich blood to the heart. These atherosclerotic plaques frequently rupture, which may cause a clot to form and in turn cut off blood flow. The end result? A myocardial infarction (MI), commonly known as a heart attack. Yet for some time, scientists have understood that before the attack actually occurs, inflammation strips the artery walls of endothelial cells, and so, circulating endothelial cells (CECs) are present within the blood.

For this reason, the team of researchers led by Kuhn hypothesized that developing a technique to measure the number of CECs might serve as a diagnostic tool for patients with troublesome symptoms — patients on the brink of a heart attack. They developed a procedure called the High-Definition Circulating Endothelial Cell (HD-CEC) assay to detect and characterize CECs in blood samples and tested it on 79 patients who had experienced a heart attack at the time of sampling. They also tested the new assay on two groups, consisting of 25 healthy patients and seven patients undergoing treatment for vascular disease, and compared all the results.

The researchers discovered the assay was able to correctly identify CECs by their morphological features as well as their reactions with specific antibodies. More importantly, the assay was able to detect them with high sensitivity and high specificity while also showing their numbers to be significantly elevated in the heart attack patients compared to the healthy controls. “These features bring within reach the eventual clinical goal of using a CEC assay as a robust diagnostic biomarker to determine which patients are at highest or imminent risk of a heart attack,” the authors wrote.

Pressure, tightness, pain, or a squeezing sensation in your chest or arms

A feeling of fullness, nausea, indigestion, heartburn, or abdominal pain

Shortness of breath

Sweating or a cold sweat

Fatigue

Trouble sleeping

Lightheadedness or dizziness

Anxiety or an impending sense of doom

During an attack, symptoms may last 30 minutes or longer. Many people who experience a heart attack have warning signs and symptoms hours, days, or even weeks in advance, though in some cases they strike without warning.